xref: /openbmc/linux/net/x25/x25_in.c (revision 22246614)
1 /*
2  *	X.25 Packet Layer release 002
3  *
4  *	This is ALPHA test software. This code may break your machine,
5  *	randomly fail to work with new releases, misbehave and/or generally
6  *	screw up. It might even work.
7  *
8  *	This code REQUIRES 2.1.15 or higher
9  *
10  *	This module:
11  *		This module is free software; you can redistribute it and/or
12  *		modify it under the terms of the GNU General Public License
13  *		as published by the Free Software Foundation; either version
14  *		2 of the License, or (at your option) any later version.
15  *
16  *	History
17  *	X.25 001	Jonathan Naylor	  Started coding.
18  *	X.25 002	Jonathan Naylor	  Centralised disconnection code.
19  *					  New timer architecture.
20  *	2000-03-20	Daniela Squassoni Disabling/enabling of facilities
21  *					  negotiation.
22  *	2000-11-10	Henner Eisen	  Check and reset for out-of-sequence
23  *					  i-frames.
24  */
25 
26 #include <linux/errno.h>
27 #include <linux/kernel.h>
28 #include <linux/string.h>
29 #include <linux/skbuff.h>
30 #include <net/sock.h>
31 #include <net/tcp_states.h>
32 #include <net/x25.h>
33 
34 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
35 {
36 	struct sk_buff *skbo, *skbn = skb;
37 	struct x25_sock *x25 = x25_sk(sk);
38 
39 	if (more) {
40 		x25->fraglen += skb->len;
41 		skb_queue_tail(&x25->fragment_queue, skb);
42 		skb_set_owner_r(skb, sk);
43 		return 0;
44 	}
45 
46 	if (!more && x25->fraglen > 0) {	/* End of fragment */
47 		int len = x25->fraglen + skb->len;
48 
49 		if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
50 			kfree_skb(skb);
51 			return 1;
52 		}
53 
54 		skb_queue_tail(&x25->fragment_queue, skb);
55 
56 		skb_reset_transport_header(skbn);
57 
58 		skbo = skb_dequeue(&x25->fragment_queue);
59 		skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
60 					  skbo->len);
61 		kfree_skb(skbo);
62 
63 		while ((skbo =
64 			skb_dequeue(&x25->fragment_queue)) != NULL) {
65 			skb_pull(skbo, (x25->neighbour->extended) ?
66 					X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
67 			skb_copy_from_linear_data(skbo,
68 						  skb_put(skbn, skbo->len),
69 						  skbo->len);
70 			kfree_skb(skbo);
71 		}
72 
73 		x25->fraglen = 0;
74 	}
75 
76 	skb_set_owner_r(skbn, sk);
77 	skb_queue_tail(&sk->sk_receive_queue, skbn);
78 	if (!sock_flag(sk, SOCK_DEAD))
79 		sk->sk_data_ready(sk, skbn->len);
80 
81 	return 0;
82 }
83 
84 /*
85  * State machine for state 1, Awaiting Call Accepted State.
86  * The handling of the timer(s) is in file x25_timer.c.
87  * Handling of state 0 and connection release is in af_x25.c.
88  */
89 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
90 {
91 	struct x25_address source_addr, dest_addr;
92 
93 	switch (frametype) {
94 		case X25_CALL_ACCEPTED: {
95 			struct x25_sock *x25 = x25_sk(sk);
96 
97 			x25_stop_timer(sk);
98 			x25->condition = 0x00;
99 			x25->vs        = 0;
100 			x25->va        = 0;
101 			x25->vr        = 0;
102 			x25->vl        = 0;
103 			x25->state     = X25_STATE_3;
104 			sk->sk_state   = TCP_ESTABLISHED;
105 			/*
106 			 *	Parse the data in the frame.
107 			 */
108 			skb_pull(skb, X25_STD_MIN_LEN);
109 			skb_pull(skb, x25_addr_ntoa(skb->data, &source_addr, &dest_addr));
110 			skb_pull(skb,
111 				 x25_parse_facilities(skb, &x25->facilities,
112 						&x25->dte_facilities,
113 						&x25->vc_facil_mask));
114 			/*
115 			 *	Copy any Call User Data.
116 			 */
117 			if (skb->len >= 0) {
118 				skb_copy_from_linear_data(skb,
119 					      x25->calluserdata.cuddata,
120 					      skb->len);
121 				x25->calluserdata.cudlength = skb->len;
122 			}
123 			if (!sock_flag(sk, SOCK_DEAD))
124 				sk->sk_state_change(sk);
125 			break;
126 		}
127 		case X25_CLEAR_REQUEST:
128 			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
129 			x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
130 			break;
131 
132 		default:
133 			break;
134 	}
135 
136 	return 0;
137 }
138 
139 /*
140  * State machine for state 2, Awaiting Clear Confirmation State.
141  * The handling of the timer(s) is in file x25_timer.c
142  * Handling of state 0 and connection release is in af_x25.c.
143  */
144 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
145 {
146 	switch (frametype) {
147 
148 		case X25_CLEAR_REQUEST:
149 			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
150 			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
151 			break;
152 
153 		case X25_CLEAR_CONFIRMATION:
154 			x25_disconnect(sk, 0, 0, 0);
155 			break;
156 
157 		default:
158 			break;
159 	}
160 
161 	return 0;
162 }
163 
164 /*
165  * State machine for state 3, Connected State.
166  * The handling of the timer(s) is in file x25_timer.c
167  * Handling of state 0 and connection release is in af_x25.c.
168  */
169 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
170 {
171 	int queued = 0;
172 	int modulus;
173 	struct x25_sock *x25 = x25_sk(sk);
174 
175 	modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
176 
177 	switch (frametype) {
178 
179 		case X25_RESET_REQUEST:
180 			x25_write_internal(sk, X25_RESET_CONFIRMATION);
181 			x25_stop_timer(sk);
182 			x25->condition = 0x00;
183 			x25->vs        = 0;
184 			x25->vr        = 0;
185 			x25->va        = 0;
186 			x25->vl        = 0;
187 			x25_requeue_frames(sk);
188 			break;
189 
190 		case X25_CLEAR_REQUEST:
191 			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
192 			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
193 			break;
194 
195 		case X25_RR:
196 		case X25_RNR:
197 			if (!x25_validate_nr(sk, nr)) {
198 				x25_clear_queues(sk);
199 				x25_write_internal(sk, X25_RESET_REQUEST);
200 				x25_start_t22timer(sk);
201 				x25->condition = 0x00;
202 				x25->vs        = 0;
203 				x25->vr        = 0;
204 				x25->va        = 0;
205 				x25->vl        = 0;
206 				x25->state     = X25_STATE_4;
207 			} else {
208 				x25_frames_acked(sk, nr);
209 				if (frametype == X25_RNR) {
210 					x25->condition |= X25_COND_PEER_RX_BUSY;
211 				} else {
212 					x25->condition &= ~X25_COND_PEER_RX_BUSY;
213 				}
214 			}
215 			break;
216 
217 		case X25_DATA:	/* XXX */
218 			x25->condition &= ~X25_COND_PEER_RX_BUSY;
219 			if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
220 				x25_clear_queues(sk);
221 				x25_write_internal(sk, X25_RESET_REQUEST);
222 				x25_start_t22timer(sk);
223 				x25->condition = 0x00;
224 				x25->vs        = 0;
225 				x25->vr        = 0;
226 				x25->va        = 0;
227 				x25->vl        = 0;
228 				x25->state     = X25_STATE_4;
229 				break;
230 			}
231 			x25_frames_acked(sk, nr);
232 			if (ns == x25->vr) {
233 				if (x25_queue_rx_frame(sk, skb, m) == 0) {
234 					x25->vr = (x25->vr + 1) % modulus;
235 					queued = 1;
236 				} else {
237 					/* Should never happen */
238 					x25_clear_queues(sk);
239 					x25_write_internal(sk, X25_RESET_REQUEST);
240 					x25_start_t22timer(sk);
241 					x25->condition = 0x00;
242 					x25->vs        = 0;
243 					x25->vr        = 0;
244 					x25->va        = 0;
245 					x25->vl        = 0;
246 					x25->state     = X25_STATE_4;
247 					break;
248 				}
249 				if (atomic_read(&sk->sk_rmem_alloc) >
250 				    (sk->sk_rcvbuf >> 1))
251 					x25->condition |= X25_COND_OWN_RX_BUSY;
252 			}
253 			/*
254 			 *	If the window is full Ack it immediately, else
255 			 *	start the holdback timer.
256 			 */
257 			if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
258 				x25->condition &= ~X25_COND_ACK_PENDING;
259 				x25_stop_timer(sk);
260 				x25_enquiry_response(sk);
261 			} else {
262 				x25->condition |= X25_COND_ACK_PENDING;
263 				x25_start_t2timer(sk);
264 			}
265 			break;
266 
267 		case X25_INTERRUPT_CONFIRMATION:
268 			x25->intflag = 0;
269 			break;
270 
271 		case X25_INTERRUPT:
272 			if (sock_flag(sk, SOCK_URGINLINE))
273 				queued = !sock_queue_rcv_skb(sk, skb);
274 			else {
275 				skb_set_owner_r(skb, sk);
276 				skb_queue_tail(&x25->interrupt_in_queue, skb);
277 				queued = 1;
278 			}
279 			sk_send_sigurg(sk);
280 			x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
281 			break;
282 
283 		default:
284 			printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
285 			break;
286 	}
287 
288 	return queued;
289 }
290 
291 /*
292  * State machine for state 4, Awaiting Reset Confirmation State.
293  * The handling of the timer(s) is in file x25_timer.c
294  * Handling of state 0 and connection release is in af_x25.c.
295  */
296 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
297 {
298 	switch (frametype) {
299 
300 		case X25_RESET_REQUEST:
301 			x25_write_internal(sk, X25_RESET_CONFIRMATION);
302 		case X25_RESET_CONFIRMATION: {
303 			struct x25_sock *x25 = x25_sk(sk);
304 
305 			x25_stop_timer(sk);
306 			x25->condition = 0x00;
307 			x25->va        = 0;
308 			x25->vr        = 0;
309 			x25->vs        = 0;
310 			x25->vl        = 0;
311 			x25->state     = X25_STATE_3;
312 			x25_requeue_frames(sk);
313 			break;
314 		}
315 		case X25_CLEAR_REQUEST:
316 			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
317 			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
318 			break;
319 
320 		default:
321 			break;
322 	}
323 
324 	return 0;
325 }
326 
327 /* Higher level upcall for a LAPB frame */
328 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
329 {
330 	struct x25_sock *x25 = x25_sk(sk);
331 	int queued = 0, frametype, ns, nr, q, d, m;
332 
333 	if (x25->state == X25_STATE_0)
334 		return 0;
335 
336 	frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
337 
338 	switch (x25->state) {
339 		case X25_STATE_1:
340 			queued = x25_state1_machine(sk, skb, frametype);
341 			break;
342 		case X25_STATE_2:
343 			queued = x25_state2_machine(sk, skb, frametype);
344 			break;
345 		case X25_STATE_3:
346 			queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
347 			break;
348 		case X25_STATE_4:
349 			queued = x25_state4_machine(sk, skb, frametype);
350 			break;
351 	}
352 
353 	x25_kick(sk);
354 
355 	return queued;
356 }
357 
358 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
359 {
360 	int queued = x25_process_rx_frame(sk, skb);
361 
362 	if (!queued)
363 		kfree_skb(skb);
364 
365 	return 0;
366 }
367